Treg limit CD8+ T-cell expansion when antigen is presented by activated but not steady-state DC.

<p>A) C57Bl/6 mice were administered 10 nmol CpG i.v. or left untreated. Eighteen hours later spleens were harvested, digested and DC subsets analysed by flow cytometry. Plots are representative of one mouse of 2–3 analysed in each of 2 separate experiments. B-D) 11c.OVA mice were injected with αCD25 or isotype-control mAb and 3 days later 2×10⁶ CD45.1+ OT-I T-cells were transferred with or without CpG administration at the time of transfer. Additional αCD25 or isotype-control mAb (iso) were administered every 3 days after the initial injection. At the times shown the total number of OT-I (CD45.1⁺CD8⁺Vα2⁺) T cells in the inguinal LN (B) or spleen (C) or at day 7 the number of CD4+CD25+FoxP3+ Treg in spleen were determined using a FACS-based assay. Data were pooled from more than 2 independent experiments (B,C; n = 5–12/group except day 1 where n = 2/group) and bars show mean ± SEM or 2 experiments (D; n = 5 or 6). (B)***: 11c+CpG+αCD25 is greater than others at day 7 (p<0.001) (C) **: 11c+CpG+αCD25 and 11c+CpG are greater than others at day 3 and day 10 (p<0.01), ***: 11c+CpG+αCD25 is greater than others at day 7 (p<0.001).